Computer Networks

Suresh Khanal electronic discipline processing system net incomeing Short Questions and Answer www. psexam. com Computer engagementing Short Questions and Answers Suresh Khanal Kalanki, capital of Nepal net ring mailprotected com electronic mailprotected com make By http//www. psexam. com contact emailprotected com Computer net incomeing Short Questions and Answers Published by PS testing Kalanki, Kathmandu Nepal www. psexam. com Copyright 2009 author.No part of this publication may be reproduced, stored in a retrieval placement or genetic in alin concert form or by any way of life, electronic, mechanical, photocopying, recording, s piece of tail or unlikewise except for personal and non-commercial role with break through the prior write permission of the author. Ab divulge the Author Suresh Khanal is a native of Kathmandu, Nepal, where he kit and caboodle as a freelance developer, programmer and technical writer/editor. He has been involved in t single outlyi ng nurture litigateing systems science since 1998 and oer the years has write several articles and tutorials on Office actions and electronic profit Programming.Khanal holds a Masters of Science degree in Information Technology Science. In his sp ar m, he enjoys travelling, c tout ensembleing card in forums and play online games. Table of Contents contagion system Media What is contagious disease media? What atomic subprogram 18 the personas of contagion media? imbibe bound infection media. Describe unbound transmission media. take a hop Transmission Media apologize wrestle orthodontic braces line of reasoning. relieve Co-axial ancestry. explain Fiber-Optics analytical argument. 1 1 1 1 1 1 1 4 5 Match the pas conviction types of surrender-to doe withors with the lineages to which they ar exercisingd. comp be BNC with UTP pipelines unbound Transmission Media rationalize communicate Wave. What is cook? distinguish the Advantages of microwave s. What argon the Disadvantages of Microwaves? Describe under Red. Computer internet What is a computing device nedeucerk? What atomic number 18 the advantages of Ne 2rking? Explain mesh work 8 9 9 10 11 11 11 12 12 12 13 What be the five major vane services? What is interlocking emcee? What is a client? What is a dedicated boniface? What is work lay? What be taciturn statusinals? Types of Computer profit What is a local argona cyberspace? What is human? What is sick of(p)? wrap up Enterprise WANs.Clarify Global WANs. What are the two types of local area earnings? Protocols What is a discourse theory protocol? What are the threesome major engagement protocols? Match the followers protocols and their sounds local area engagement Topologies What are the two electronic cyberspace conjunctive types? Explain Point-to-Point joinion type. Explain multipoint connection. What are the fundamental LAN topologies? Explain Bus topographic anatomy. What are the advantages of muckle network network network analysis situs? 13 13 13 14 14 14 15 15 16 16 16 17 17 18 18 18 19 20 20 20 21 21 21 23 What are the disadvantages of busbar topology? What is battalion regional anatomy? Point out the major advantages of sound analysis situs.Point out the disadvantages of stupendous number Topology. Explain Star Topology. What are the benefits of Star Topology? What are the disadvantages of Star Topology? What are the favourite topologies different than basic Topologies? Network Standards What is a Networking Standard? What are the four major effort standards? What is an Ethernet? How an Ethernet Worked? What is moderate access asc remainderency of Ethernet? Explain Ethernet Frame. joust some advantages of Ethernet. What are the disadvantages of Ethernet Cabling? What is ARCNet? List the advantages of ARCNet. What are the disadvantages of ARCNet?How does a token(prenominal)-Passing Protocol works? 24 24 25 25 25 26 26 27 27 27 27 28 2 8 29 29 30 30 31 32 32 32 Explain Logical battalion Physical Star topology for Token-Passing Standard. 32 List some about wontful advantages of Token Ring. 33 Point out the disadvantages of Token Ring. What do you mean by Beaconing and Auto-Reconfiguration? Network Architecture What is Network Architecture? What are the popular Network Architectures? Explain ISOs OSI Architecture Explain IBMs SNA Architecture Networking feign Explain Peer-to-Peer Networking Model. Explain client/Server Networking Model.Network and net profit Terminologies NICs Hubs/ reversionists duets Router switch overes Transceivers entrance Proxy Serer Firew either Node Wireless Network earnings WWW 34 34 34 34 35 35 36 37 37 37 38 38 39 39 40 41 42 42 43 43 43 43 45 45 IRC CU-SeeMe Telnet Gopher hypertext markup language Browsers telephone dialup Connection IP verbalize sphere Name URL weathervane Browsing or surfboard take care Engine Meta Search Engine internet Access Extranet Intranet Web gre at power Hypertext telecommunicate netmail regale Inbox Outbox Trash CC 46 47 48 49 49 50 53 53 54 54 54 55 57 57 58 58 58 59 59 59 60 60 61 61 BCC Reply forward-moving Attachments Bounced Netiquette Emoticons 62 62 62 62 62 62 62 Table of work outs foresee 1 UTP lineage 2 throw 2 UTP cablegram connexion 2 view 3 s.t.p. Cable 3 prototype 4 s.t.p. Cable expression 3 condition 5 Co-Axial Cable 4 bet 6 Co-Axial Cable Structure 4 take to 7 Co-Axial Cable conjunctives 5 public figure 8 Fibre Optics Cable Structure 6 epithet 9 Fiber Optics Cable 6 number 10 AUI Connector 7 go through 11 BNC Connector 7 regard 12 RJ45 Connector 8 take care 13 SC Connector 8 figure 14 Comparison amongst perverted twains and Co-Axial Cable 9 regard 15 Radio Wave Transmission 9 ensure 16 Microwave Transmission 10 manikin 17 Microwave Transmitter, Receiver and Repeater 10 Figure 18 Infrared Device ErrorBookmark not define. Figure 19 Computer Network 12 Figure 20 Workstation 14 Figur e 21 Dumb Terminal 15 Figure 22 broad sweep Network 16 Figure 23 Enterprise WAN 17 Figure 24 TCP/IP Structure 18 Figure 25 IPX/SPX Structure 19 Figure 26 different LAN Topologies 20 Figure 27 Bus Topology 21 Figure 28 Bus Topology Network machine- annoyible with former(a)(a) network 22 Figure 29 T Connector 22 Figure 30 opposite Cable Terminators 23 Figure 31 Ring Topology 24 Figure 32 Star Topology 25 Figure 33 Star Topology 26 Figure 34 Tre Topology Error Bookmark not defined. Figure 35 Mesh Topology Error Bookmark not defined.Figure 36 Ethernet Network 29 Figure 37 ARCNet get on with and account 31 Figure 38 Network with MSAU 33 Figure 39 ISOs OSI Architecture 35 Figure 40 OSI an SNA Comparision 36 Figure 41 LAN NIC Card 38 Figure 42 Hub 39 Figure 43 twosome 40 Figure 44 Router 41 Figure 45 Switch 41 Figure 46 Transceiver 42 Figure 47 access PC 43 Figure 48 Nework with Wireless Stations 44 Figure 49 Tim Berners lee 45 Figure 50 yahoo Chat 46 Figure 51 CU SeeMe 47 Figu re 52 CU SeeMe Conferencing 48 Figure 53 Telnet Screen 48 Figure 54 variant Browsers Logo 50 Figure 55 Mozilla Firefox 51 Figure 56 Netscape Navigator 51 Figure 57 Internet venturer 52 Figure 58 Google Chrome 52 Figure 59 IP predict Structure 53 Figure 60 IP Address and Subnet Mask 53Figure 61 hick, Ask, MSN, Google Search Engines Figure 62 Alta Vista Search Engine Figure 63 Lycos Figure 64 Meta Search Engine Figure 65 Web Index Figure 66 Hypertext and Hyper middleman Figure 67 Email Client Interface Figure 68 New Email kernel Figure 69 Emoticons 55 56 56 57 58 59 60 61 63 Computer Networking Short Questions and Answers Suresh Khanal Kalanki, Kathmandu emailprotected com emailprotected com Published By http//www. psexam. com contact emailprotected com Computer Networking Short Questions and Answers parting of Suresh Khanal for PS examination Transmission Media What is transmission media? Transmission media is a caterpillar trackway through which entropy are intercommunicate ted in network.We use different types of cables or waves to transmit study. What are the types of transmission media? There are two types of transmission media viz. bound transmission media and unbound transmission media. Describe bound transmission media. Bound transmission media are the cables that are tangible or fix physical existence and are limited by the physical geography. normal bound transmission media in use are twisted braces cable, co-axial cable and persona optical cable. Describe unbound transmission media. detach transmission media are the ways of transmitting information without use any cables. These media are not bounded by physical geography.Microwave, Radio wave, Infra red are some of popular unbound transmission media. Bound Transmission Media Explain twisted pair cable. A pair of telegraphs twisted with each different is kn stimulate as twisted pair cable. A association of four pairs of twisted wires are bundled to form cable. These are the roug hly common strength for LAN. Wires are twisted with each some other(prenominal) so as to reduce the interference. http//www. psexam. com knave 1 division of Suresh Khanal for PS tryout Figure 1 UTP Cable Figure 2 UTP Cable Connector varlet 2 http//www. psexam. com function of Suresh Khanal for PS exam We give the sack decree two types of twisted pair cables, namely Un shielded Twisted Pair Cable (UTP) and Shielded Twisted Pair Cable (STP).The twisted pair cable that is protected against electro-magnetic interference (EMI) is k straightwayn as STP and the integrity which is not shielded against EMI is called Unshielded Twisted Pair. Figure 3 STP Cable 1Jacket 2Shield-braid 3Shield-foil 4 consentaneous twisted pair 5Drain wire Figure 4 STP Cable Structure http//www. psexam. com pageboy 3 theatrical role of Suresh Khanal for PS mental testing Explain Co-axial cable. A solid central conductor surround by insulating material and then by a cylindrical shield woven from fine wires is cognise as co-axial cable. The shield is unremarkably machine-accessible to electrical ground to reduce electrical interference. Co-axial cables have broader bandwidth and thus adequate for audio, video selective information transmission. Figure 5 Co-Axial Cable Figure 6 Co-Axial Cable Structure page 4 http//www. psexam. com compvirtuosont of Suresh Khanal for PS test Figure 7 Co-Axial Cable Connectors Explain Fiber-Optics cable. A cable with central glass thermionic tube covered with protective shield which transmit data victimisation photons is fiber optics cable. These cables transmit data via concentrated bursts of laser shaft of lights which are carried through bundles of tomentum cerebri thin glass fibers. They have advantages over electronic cables in transmission speed and volume. This technology has revolutionized telecommunication applications which utilise electronic cables. Fiber optics cables as free from electromagnetic interference as intumesce as wire tapping. http//www. sexam. com scalawag 5 contribution of Suresh Khanal for PS interrogation Figure 8 Fibre Optics Cable Structure Figure 9 Fiber Optics Cable page 6 http//www. psexam. com part of Suresh Khanal for PS Exam Match the followers types of connectors with the cables to which they are utilize. Cable (a) Thick Coax (100 Base 5), (b) UTP (10 Base-T), (c) Fiber Optics (10 Base-FL) (d) concentrate Coax (100 Base 5) Connectors (1) AUI, (2) BNC, (3) RJ45, (4) SC or ST Type Answer- a - 1, b - 3, c - 4, d - 2 Figure 10 AUI Connector Figure 11 BNC Connector http//www. psexam. com paginate 7 piece of Suresh Khanal for PS Exam Figure 12 RJ45 ConnectorFigure 13 SC Connector Compare BNC with UTP Cables BNC Derived from the thick Ethernet Coaxial Cable Flexibility of adding lymph guests Lower price and no need of Hub Difficult to locate faults Terminators needed The cabling is comparatively less bona fide Single discussion section length (node to node) up to 180 m eters UTP Derived from teleph unmatchable cable Decided by Hub ports Needs Hubs Introduction of Hub makes fault finding much easier Terminators not needed Inherently much reliable Single segment length up to 200 meters rogue 8 http//www. psexam. com component of Suresh Khanal for PS Exam Figure 14 Comparison amid Twisted Pairs and Co-Axial Cable Unbound Transmission MediaUnbound transmission media ext cobblers last beyond the limiting moderate of cabling. They provide an handsome communication alternative for WANS. The lack of physical restrictions provides big bandwidth as healthful as wide area capabilities. Unbound media typically draw at really gamy frequencies. The three types of unbound transmission media are Radio wave, Micro wave, Infrared Explain Radio Wave. Although Radio waves are prevalent and well understood, we are just beginning to draw in their enormous potential as a networking medium. Radio waves locoweed operate on a single or multiple oftenness ban ds. Figure 15 Radio Wave Transmission http//www. psexam. com Page 9 share of Suresh Khanal for PS Exam What is Microwave?Microwaves have been used in data communications for a long time. They have a high uper relative frequency than radio waves and therefore plenty pass over adultr beats of data. Microwave transmission is line of freshet transmission. The transmit station mustiness be in visible contact with the rule station. This sets a limit on the keep amid stations depending on the local geography. Typically the line of sight due to the Earths curvature is unaccompanied 50 km to the horizon Repeater stations must be placed so the data preindication can hop, skip and jump across the country. Figure 16 Microwave Transmission Figure 17 Microwave Transmitter, Receiver and Repeater Page 10 http//www. psexam. com piece of Suresh Khanal for PS Exam Microwaves operate at high film frequencies of 3 to 10 GHz. This allows them to carry large quantities of data due to their large bandwidth. List the Advantages of microwaves. a. They require no right of way acquisition between towers. b. They can carry high quantities of information due to their high direct frequencies. c. Low cost land purchase each tower occupies lone(prenominal) a low area. d. High frequency/short wavelength shows require diminutive antennae. What are the Disadvantages of Microwaves? a. Attenuation by solid objects birds, rain, snow and fog. b. Reflected from flat surfaces kindred water and metal. c. Diffracted (split) around solid objects. d.Refracted by atmosphere, thus ca utilize beam to be projected away from receiver. Describe Infra Red. Infrared offers a great unbound photonic solution. Like fiber-optic cabling, infrared communications use light, so they are not bound by the limitations of electricity. Figure 18 Infrared Device http//www. psexam. com Page 11 voice of Suresh Khanal for PS Exam Computer Network What is a reckoner network? Computer Network is a collection of distributed intelligent machines that are connected with each other with transmission media for the purpose of data sha closed chain, communication and sharing of computer resources. Figure 19 Computer NetworkWhat are the advantages of Networking? The followers are the distinct notes in favor of computer networking. a. The computers, staff and information can be well managed b. A network provides the meat to exchange data among the computers and to make programs and data available to people c. It permits the sharing of the resources of the machine d. Networking also provides the function of back-up. e. Networking provides a flexible networking environment. Employees can work at home by using through networks ties through networks into the computer at office. Page 12 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Explain Network functionNetwork services are the social occasion that a network can do. The major networking services are ? ? ? ? ? level func tion This includes consign transfer, storage, data migration, file update, synchronization and achieving. Printing service This service produces shared access to valuable printing artifices. Message Services This service facilitates email, voice mails and coordinate object oriented applications. act Services This services allows to centralize high profile applications to increase performance and scalability Database Services This involves coordination of distributed data and replication. What are the five major network services? study Network Services are a. b. c. d. e.File Services Print Services Message Services Application Services Database Services What is Network Server? Network Server is a computer in Network that is designated to provide one or more(prenominal) network service. For sheath file host, database processr and so forth What is a client? A computer in network that connects to the host and uses the network services to perform drug substance absubstance a b users tasks is a client. http//www. psexam. com Page 13 Contribution of Suresh Khanal for PS Exam What is a dedicated server? A network server designated to provide one particular service is cognise as dedicated server. For workout if a computer is assigned for database service unless then that computer is known as dedicated database server. What is workstation?A workstation is a node in network that is more sinewy and can handle local information processing or graphics processing. A workstation usually has an threepenny, small hard disk to carry out local tasks. Figure 20 Workstation Some workstations that have no disk drive of their own is known as diskless-workstation or silent terminals. They terminals solely rely on LAN for their access. Network operational system lets the node work as if all the resources at the server hold up to the node itself. What are dumb terminals? Those Workstations that have no disk drive of their own and rely completely on LAN for their ac cess are called dumb terminals.The network operational system lets these terminals work as if all the resources at the server belong to the workstation itself. Page 14 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Figure 21 Dumb Terminal Types of Computer Network Computer networks fall into three classes regarding the size, distance and the structure namely LAN (Local Area Network), MAN (Metropolitan Area Network), WAN ( good Area Network). A LAN neckties a small group of functionally homogeneous workstations inside a local geo graphic area such as a series of adjacent cubicles or offices on the corresponding floor. Once the network expands to include other floors or divers office deep down a metropolitan area, it becomes a MAN. Finally, a WAN is alone a LAN of LANs.WANs expand the boundaries of networking to a globose or even galactic scale. What is a LAN? A LAN is a Local Area Network, within a single building or a specific confined space. LANs typicall y comprise single one transmission media type such as coaxial cable or twisted pair. LANs are characterized by comparatively high-speed communications. These high speeds are possible because LANs use one kind of cable which slackly is limited to 5 km or less. http//www. psexam. com Page 15 Contribution of Suresh Khanal for PS Exam What is MAN? MAN stands for Metropolitan Area Networks. MAN is bigger than a LAN and as its name implies, covers the area of a single city.MANs rarely extend beyond 100 KM and frequently comprise a combination of different hardware and transmission media. The two around important components of MANs are security and standardization. Security is important because information is being shared between dissimilar systems. Standardization is necessary to run across reliable data communication. What is WAN? A wide area network is simply a LAN of LANs. WANs connect LANs that may be on opposite sides of a building, across the country or around the area. WANS a re characterized by the impenetrableest data communication rates and the largest distances. WANs can be of two types an enterprise WAN and Global WAN. Figure 22 Wide Area NetworkClarify Enterprise WANs. An enterprise WAN connects an entire system of rules including all LANs at various sites. This term is used for large, widesp con organizations such as corporations, universities and governments. Page 16 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Figure 23 Enterprise WAN Clarify Global WANs. Global WANs also tangle the world but they do not have to connect LANS within a single organization. The Internet is an example of a global WAN. It connects versatile locations, organizations and institutions throughout the world. Global WANS can be public or private. secret WANs are called Intranet which belongs to an organization.Public WANs are open to everybody so that anybody can connect and use the resources and services available. What are the two types of LAN? T here are fundamentally two types of Local Area Networks namely Arcnet and Ethernet. http//www. psexam. com Page 17 Contribution of Suresh Khanal for PS Exam Protocols What is a protocol? The term protocol refers to a set of rules and procedures that govern the transmission of pass ons over a physical networking medium. The intimately common network protocols are (a) TCP/IP, (b) IPX/SPX and (c) NetBEUE What are the three major network protocols? The three major network protocols are 1. TCP/IP 2. IPX/SPX (Used in Novell Netware) 3. NetBEUE (Product of Microsoft Co. ) Figure 24 TCP/IP StructurePage 18 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Figure 25 IPX/SPX Structure Match the following protocols and their functions (a) http, (b) pop, (c) ftp, (d) smtp, (e) MIME, 1. Send email nitty-grittys 2. Transfer multimedia information 3. Send email attachment 4. Transfer files in servers and clients computers 5. Receive email messages Answer (a) - 2, (b) - 5, (c) - 4 , (d) - 1, (e) - 3 http//www. psexam. com Page 19 Contribution of Suresh Khanal for PS Exam LAN Topologies The term topology defines the geographic arrangement of networking widgets. It describes the actual layout of the network hardware.Given the location of workstations and peripherals, the determination of topology is to find the or so economical and efficient way to connect all the users to the network resources charm providing adequate capacity to handle user demands, maintain system reliability and minimize delay. Figure 26 Different LAN Topologies The selection of a topology for a network can not be done in isolation as it affects the select of media and the access method used. Because it determines the strategy used in wiring a building for a network and deserves some careful study. What are the two network connection types? The two different network connection types are (a) point-to-point connection and (b) multipoint connection. Explain Point-to-Point connection type. A point-to-point connection is a direct think between two devices such as a computer and a printer.Most of todays point-to-point connections are associated with modems and PSTN (Public Switched Telephone Network) communications. Page 20 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Explain multipoint connection. A multipoint connection is a link between three or more devices. Historically, multipoint connections were used to attach central bike to distributed dumb terminals. In todays LAN environments, multipoint connections link many network devices in various configurations. What are the basic LAN topologies? The three simple LAN topologies that are combined to form any working topology are known as basic LAN topologies.They are, Bus Topology, Ring Topology and Star Topology. Explain Bus Topology. The physical Bus topology is the simplest and just about widely used of the network designs. It consists of one continuous length of cable (trunk) and a terminati ng resistor (terminator) at each end. Data communication message travels on the bus in both directions until it is picked up by a workstation or server NIC. If the message is missed or not recognized, it reaches the end of the cabling and dissipates at the terminator. Figure 27 Bus Topology http//www. psexam. com Page 21 Contribution of Suresh Khanal for PS Exam All nodes on the bus topology have equal access to the trunk.This is accomplished using short beading cables or direct T-connectors. The number of devices and the length of the trunk can be intimately expanded. Figure 28 Bus Topology Network connected with other network Figure 29 T Connector Page 22 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Figure 30 Different Cable Terminators What are the advantages of bus topology? The advantages of physical bus topology are a. It uses established standards and it is relatively unaccented to install. b. It requires less media than other topologies. http//www. ps exam. com Page 23 Contribution of Suresh Khanal for PS Exam What are the disadvantages of bus topology?The disadvantages of bus topology are a. The bus networks are uncorrectable to reconfigure, particularly when the acceptable number of connections or maximum distances have been reached. b. They are also difficult to troubleshoot because everything happens on a single media segment. This can have solemn consequences because any break in the cabling brings the network to its knee. What is Ring Topology? The physical ring topology is a circular draw in of point-to-point links. Each device connects directly to the ring or indirectly through and interface device or drop cable. Message travel around the ring from node to node in a very organized manner.Each workstation checks the message for a matching destination grapple. If the address doesnt match the node simply regenerates the message and delegates it on its way. If the address matches, the node accepts the message and sends a reply to the originating sender. Figure 31 Ring Topology Page 24 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Point out the major advantages of Ring Topology. The advantages of ring topologies are a. They are very easy to troubleshoot because each device incorporates a repeater. b. A special(prenominal) internal feature called beaconing allows troubled workstations to unwrap themselves quickly. Point out the disadvantages of Ring Topology.The disadvantages of ring topologies are a. It is considerably difficult to install and reconfigure ring topology b. Media ill fortune on unidirectional or single loop causes complete network failure. Explain Star Topology. The physical thaumaturge topology uses a central controlling hub with dedicated legs pointing in all directions wish well points of a one. Each network device has a dedicated point-to-point link to the central hub. This strategy prevents troublesome collisions and keeps the lines of communications op en and free of traffic. Figure 32 Star Topology http//www. psexam. com Page 25 Contribution of Suresh Khanal for PS Exam This topology, obviously, require a great deal of cabling.This design provides an exquisite platform for reconfiguration and troubleshooting. Changes to the network are as simple as plugging another(prenominal) segment into the hub and a break in the LAN is easy to insulate and doesnt affect the rest of the network. Figure 33 Star Topology What are the benefits of Star Topology? The benefits of star topology are a. Relatively easy to configure. b. Easy to troubleshoot c. Media faults are automatically isolated to the failed segment. What are the disadvantages of Star Topology? The disadvantages are considered as follows a. Requires more cable than most topologies. b. Moderately difficult to install. Page 26 http//www. sexam. com Contribution of Suresh Khanal for PS Exam What are the popular topologies other than basic Topologies? Apart from basic topologies some other topologies outlay considering are mesh topology (every device connected to all other devices), Cellular Topology ( receiving set point to pint and multipoint design), Tree Topology (Hierarchical connections of devices), loanblend topology (combination of two or more basic topologies). Figure 34 Tre Topology Figure 35 Mesh Topology Network Standards What is a Networking Standard? Protocol (the logical component) and Topology (the physical component) is combined in concert to create a networking standard.These standards are veritable and controlled by the Institute of electrical and Electronics Engineers (IEEE). What are the four major industry standards? The four major industry standards are (a) Ethernet, Token Ring, ARCNet and FDDI (Fiber Distributed Data Interface). http//www. psexam. com Page 27 Contribution of Suresh Khanal for PS Exam What is an Ethernet? The Ethernet topology was developed at the University of Hawaii to connect computers on the various Islands. It wa s radio based design. Later, Robert Metacalfe went to Xeross Palo Alto Research Center (PARC) laboratories and eliminated the radio portion and changed to co-axial cabling. Ethernet is ne of the most popular LAN technologies in use today covering more than 85% of the networks. Ethernet system consists of three basic divisions 4. The physical medium use to carry Ethernet signals between computers on the network 5. A set of rules (protocols) embedded in each Ethernet interface that leave behind decide how multiple computers on the network will have access to the data on the medium. 6. An Ethernet butt that consists of a standardized set of bits used to carry data over the system. How an Ethernet Worked? The operation of Ethernet can be set forth in simple terms as follows Each computer on the Ethernet Network, also known as a node, operates independently of all other nodes.All nodes attached to an Ethernet are connected to a shared medium over which the Ethernet signals travel ser ially, one data bit at a time. To send data a station first listens to the channel and when the channel is swig the station transmits its information in the form of an Ethernet put up, or software package. The Ethernet rules (protocol) are defined in such a way that every node gets a fair amount of frame transmission opportunity. Page 28 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Figure 36 Ethernet Network As each Ethernet frame is sent out on the shared medium, the Ethernet interfaces inside the node look at the destination address.The interfaces compare the destination address of the frame with their own address. The Ethernet interface with the same address as the destination address in the frame will read the entire frame and all other network interfaces will ignore the information. What is long suit Access Control of Ethernet? The set of rules which ensures that every node in an Ethernet gets a fair amount of frame transmission opportunity, are called the Medium Access Control mechanism. The Medium Access Control mechanism is based on a system called Carrier Sense Multiple Access with Collision Detection (CSMD/CD). Explain Ethernet Frame. The heart of Ethernet system is the Ethernet Frame, which is used to deliver information between the computers.The frame consists of a set of bits organized into several fields. These fields include address fields, a data field and an error checking field that checks the integrity of the bits in the frame to make sure that the frame has arrived intact. http//www. psexam. com Page 29 Contribution of Suresh Khanal for PS Exam List some advantages of Ethernet. Ethernets major advantages are 1. It is an inexpensive way to achieve high speed LAN transmissions (10 to 100 MB/s) 2. It is a proven technology that stand outs various writing configurations. 3. It works well with a large number of LAN and micro-tomainframe applications. 4. It is easy to install. What are the disadvantages of Ethernet Cabli ng?The Ethernet cabling ahs the following disadvantages 1. Ethernet is not a high-level performer in high-load environments. This protocol (CSMA/CD Carrier Sense Multiple Access/Collision Detection) can slow down dramatically if hundreds of workstations are competing for the same cabling trunk 2. Its linear bus cabling system can sometimes make it difficult to isolate problems. Page 30 http//www. psexam. com Contribution of Suresh Khanal for PS Exam What is ARCNet? The Attached Resource Computer Network (ARCNet) standard was created in 1977 at the Data Point gage by a scientist John Murphy. ARCNet uses the token-passing protocol over a star and bus topology.The star and bus topology combines the flexibility of a star with the simplicity and throughput of a bus. Thus, ARCNet standard has a unique protocol/topology combination token-passing protocol and Distributed star/bus topology. Figure 37 ARCNet Board and Card http//www. psexam. com Page 31 Contribution of Suresh Khanal for PS Exam List the advantages of ARCNet. Here are some of the ARCNets advantages 1. It is extremely reliable. 2. ARCNet is easy to install and troubleshoot. 3. It has an excellent track record of interoperability for those using ARCNet components from various manufacturers. 4. ARCNet supports a variety of cable types including coaxial, UTP and Fiber Optics. 5.It is inexpensive and built to stay that way. What are the disadvantages of ARCNet? Here are some disadvantages of ARCNet 1. Standard ARCNet is very slow (2. 5 Mb/s). It is virtually seven times slower than Token Ring. 2. ARCNet was not intentional with interconnectivity in mind. For many installations, its difficult to go beyond the confines of single LAN. How does a Token-Passing Protocol works? The token-passing protocol relies on a control signal called the token. A token is a 24-bit packet that circulates throughout the network from NIC to NIC in an orderly fashion. If a workstation wants to transmit a message, first it must secure the token.At that point, the workstation has complete control over the communications channel. The existence of only one token eliminates the possibility of signal collisions. This means that only one station can speak at a time. Explain Logical Ring Physical Star topology for Token-Passing Standard. It is sure that any break in the ring at any point will interrupt communications for all machines. To solve this problem, IBM developed a modified ring topology, which they called the logical ring Page 32 http//www. psexam. com Contribution of Suresh Khanal for PS Exam physical star. The central point of the physical star configuration is Token Ring hub called the multi-station access unit (MSAU, pronounced as masow).Workstations and servers attached to the MSAU through special STP adapter cables. IBM born-again stars into a logical ring by connecting all MSAU hubs unitedly through special ring-in (RI) and ring-out (RO) ports. Figure 38 Network with MSAU List some most useful advantages of Token Ring. Here are Token rings most useful advantages a. It offers excellent throughput under high-load conditions. b. Token Ring facilitates LAN-to-LAN mainframe connections especially for interfacing with IBMs broader connectivity strategies. c. It has built-in troubleshooting mechanisms such as beaconing and auto-reconfiguration and may now be used with UTP cabling. http//www. psexam. com Page 33 Contribution of Suresh Khanal for PS Exam d.It has the most reliable protocol (token-passing), the most trouble-free configuration (physical star) and the prompt connectivity scheme (r or 16 mb/s). Point out the disadvantages of Token Ring. Few of the disadvantages of Token Ring are a. Token Ring is very expensive. All topology components cost much more than other more popular standards. b. It is relatively proprietary. Token Rings complexity is built into the hardware components. This means hat you need to choose a manufacturer and stick with it. c. Engineers must have considerable expertise to manage and troubleshoot token ring components. What do you mean by Beaconing and AutoReconfiguration?When a station does not receive a message from its nearest active upstream neighbor, it sends out a warning, differently known as a beacon. This beacon alerts everyone that something is wrong and inspection and repairs to isolate the failure domain. When beacon occurs, the ring will attempt to fix the problem without your intervention. This process of self-healing is called auto-reconfiguration. Network Architecture What is Network Architecture? When two or more computer are connected with one another for the purpose of communicating data electronically, besides physical connection of computers, communication devices and system servers, a well defined standard known as architecture is mandatory to establish cohesive communication between devices in Network. Page 34 http//www. psexam. om Contribution of Suresh Khanal for PS Exam What are the popular Networ k Architectures? The most popular architectures are a. ISO Open System Architecture (OSI) b. IBMs System Network Architecture (SNA) Explain ISOs OSI Architecture The Open System Interconnection (OSI) is a standard reference model for communication between two end users in a network. It is used in developing products and understanding networks which means commonly used Internet product and services fit within the model. The OSI model describes seven layers of related functions that needed at each end, when a message is sent from one party to another party in a network.Each layer has its own set of special related function as follows Figure 39 ISOs OSI Architecture http//www. psexam. com Page 35 Contribution of Suresh Khanal for PS Exam degree 7 Application Layer Application programs that use the network. Layer 6 Presentation Layer Standardize data presented to the application. Layer 5 Session Layer Manages sessions between applications Layer 4 Transport Layer Provides error dete ction and correction Layer 3 Network Layer Provides data pitch shot across the physical connection Layer 2 Data Link Layer Provides data delivery across the physical connection Layer 1 Physical Layer Defines the physical network media.Explain IBMs SNA Architecture SNA is a computer networking architecture that was developed by IBM to provide a network structure for IBM mainframe, midrange, and personal computer systems. SNA defines a set of proprietary communication protocols and message formats for the exchange and counselling of data on IBM host networks. Figure 40 OSI an SNA Comparision Page 36 http//www. psexam. com Contribution of Suresh Khanal for PS Exam SNA can be used for the following types of tasks ? Terminal access to mainframe and midrange computer applications. File transfer of data between computer systems. Printing of mainframe and midrange data on SNA printers.Program-to-program communications that allow applications to exchange data over the network. ? ? ? SNA can be implement in a networking infrastructure that uses either a hierarchical or peer-to-peer model. Networking Model Explain Peer-to-Peer Networking Model. A networking model where each workstation has equivalent capabilities and responsibilities is known as peer-to-peer model. There is no central server in this network and computers join hands to share files, printers and Internet access. It is practical for workgroups of a 12 or less computers making it common environments, where each PC acts as an independent workstation that stores data on its own disk but which can share it with all other PCs on the network.Software for peer-to-peer network is included with most modern desktop operating systems such as Windows and Mac OS. Explain Client/Server Networking Model. A networking model where one or more brawny computers (servers) provide the different network services and all other users computers (clients) access those services to perform users tasks is known as client/server networking model. Client-server networking model became popular in the late 1980s and early mid-nineties as many http//www. psexam. com Page 37 Contribution of Suresh Khanal for PS Exam applications were migrated from centralized minicomputers and mainframes to networks of persona computers.The design of applications for a distributed computing environment required that they effetely be divided into two parts client (front end) and server (back end). The network model on which they were implemented mirrored this client-server model with a users PC (the client) typically acting as the requesting machine and a more powerful server machine to which it was connected via either a LAN or a WAN acting as the supplying machine. It requires special networking operating system. It provides user level security and it is more expensive. Network and Internet Terminologies NICs Network interface cards, commonly referred to as NICs are used to connect a PC to a network.The NIC provides a physical connection between the networking medium and the computers internal bus, and is responsible for facilitating an access method to the network. Most NICs are designed for a particular type of network, protocol and media, although some can serve multiple networks. Figure 41 LAN NIC Card Page 38 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Hubs/Repeaters Hubs/Repeaters are used to connect together two or more network segments of any media type. In larger design, signal quality begins to deteriorate as segment exceeds their maximum length. A hub provides the signal amplification required to allow a segment to be extended a greater distance. Passive hub simply forwards any data packets they receive over one port from one workstation to all their remaining ports.Active hubs, also sometimes referred to as multiport repeaters, regenerate the data bits in order to maintain a strong signal. Figure 42 Hub tie The bridge function is to connect separate homogeneous networks. Bridges typify the Ethernet address of the nodes residing on each network segment and allow only necessary traffic to pass through the bridge. When a packet is current by the bridge, the bridge determines the destination and source segments. If the segments are different, then the packet is forwarded to the correct segment. Bridges are also called store-and-forward device because they look at the whole Ethernet packet before making filtering or send on decisions. ttp//www. psexam. com Page 39 Contribution of Suresh Khanal for PS Exam Figure 43 Bridge Router Routing achieved commercially popularity in the mid 1980s at a time when large-scale Internetworking began to replace the fairly simple, homogeneous environments. Routing is the act of moving information across an Internetwork from a source to a destination. It is often contrasted with bridging, which perform a similar function. Routers use information within each packet to street it from one LAN to another, and communicat e with each other and share information that allows them to determine the best route through a complex network of many LANs.Page 40 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Figure 44 Router Switches LAN switches are an expansion of the concept in LAN bridging, which controls data flow, handles transmission errors, provides physical addressing, and manages access to the physical medium. Switches provide these functions by using various link-layer protocols. LAN switches can link four, six, ten or more networks together. A storeand-forward switch, on the other hand, accepts and analyses the entire packet before forwarding it to its destination. Figure 45 Switch http//www. psexam. com Page 41 Contribution of Suresh Khanal for PS Exam TransceiversTransceivers are used to connect nodes to the various Ethernet media. Most computers and network interface cards contain a builtin 10BaseT or 10Base2 transceiver, allowing them to be connected directly to Ethernet withou t requiring an external transceiver. Many Ethernet devices provide an AUI connector to allow the user to connect to any media type via an external transceiver. Figure 46 Transceiver doorway A Gateway is a device such as a mini or microcomputer capable of operating on a stand alone basis but which also provides connection for communication with the other computers and access to shared resources. Page 42 http//www. psexam. comContribution of Suresh Khanal for PS Exam Figure 47 Gateway PC Proxy Serer Also called a proxy or application level gateway. It is an application that breaks the connection between sender and receiver. Thus, it helps us to prevent hacker from obtaining Internet address and percentage point of a private network. Firewall Firewall is a method for keeping a network secure. It is mostly used in giving users access to the Internet in a secure fashion as well as to separate a companys public clear server from its internal network. Node A node is a hardware device or group of devices or station in a network that link one or more other unit to the network. Wireless NetworkThe most and latest piano tuner LANs use electromagnetic airwaves either infrared or radio frequency to communicate information from one point to another without relaying on a physical connection. Radio waves are often referred to as radio carriers because they simply perform the function of delivering energy to a remote receiver. The http//www. psexam. com Page 43 Contribution of Suresh Khanal for PS Exam data being transmitted is pose on the radio carrier so that it can be accurately extracted at the receiving end. Multiple radio carriers can exist in the same space at the same time without interfering with each other if the radio waves are transmitted on different radio frequencies. Figure 48 Nework with Wireless StationsIn a typical WLAN configuration, a vector/receiver (transceiver) device, called an Access Point (AP), connects to the pumped up(p) network from a stock -still location using standard Ethernet cable. The Access Point receives, buffers, and transmits data between the WLAN and the Page 44 http//www. psexam. com Contribution of Suresh Khanal for PS Exam wired network infrastructures. A single Access Point can support a small group of users and can function within a range of less than one hundred to several hundred feet. The Access Point (or the antenna attached to the Access Point) is usually mounted high but may be mounted essentially anywhere that is practical as long as the desired radio coverage is obtained.The wireless network, printers or other peripherals can be shared through a connected PC. The devices then communicate using a set of reserved high-frequency radio waves. An Access Point device connects to a DSL or cable modem and enables high-rate (broadband) Internet access for the entire network. Internet Internet is the large worldwide network of computes that facilitates data communication services, file transfer, electroni c mail, populace Wide Web and newsgroup with common protocols. WWW Figure 49 Tim Berners Lee http//www. psexam. com Page 45 Contribution of Suresh Khanal for PS Exam The WWW is the intake of Tim Berners Lee a CERN who had the idea of creating an electronic net of research information.The wind vane is currently the fastest growing Internet information system, with new resources being added regularly. The web relies on a set of protocols, conventions and software to operate. The web is a distributed system of delivering linked documents over the Internet. It is called a distributed system because information can reside on different computers around the world. Yet be easily linked together using hypertext. The web uses hypertext to create links from together using hypertext. The web uses hyperte3xt to create links from one resource to another. A hypertext link is usually displayed by highlighted and underlined text on the page. A hypertext link or hyperlink can also be graphic that acts as a button linking to another resource. IRCInternet Relay Chat (IRC) is a system for displace public and private message to other users in real time that is, your message appears on the recipients screen as soon as you type it. Figure 50 bumpkin Chat Page 46 http//www. psexam. com Contribution of Suresh Khanal for PS Exam CU-SeeMe CU-SeeMe is a video conferencing system that allows users to send and receive sound and pictures simultaneously over the Internet. Figure 51 CU SeeMe http//www. psexam. com Page 47 Contribution of Suresh Khanal for PS Exam Figure 52 CU SeeMe Conferencing Telnet It is a protocol or set of rules that enables a computer to connect another computer in network. It is also known as a remote login. The telnet operates on client-server principle. Figure 53 Telnet Screen Page 48 http//www. psexam. comContribution of Suresh Khanal for PS Exam Gopher The ghoper is a protocol designed to search, reclaim and display documents from remote sites on the Interne t. The Ghoper was created as a piece of software to utilize some of the services that were becoming available on the Internet. HTML HTML stands for Hyper Text Markup Language. It is a standard coding language used to create all web documents (pages). http//www. psexam. com Page 49 Contribution of Suresh Khanal for PS Exam Browsers Figure 54 Different Browsers Logo A web rover is the Internet Client software that acts as an interface between the user and the inner-workings of the Internet, specifically the WWW.We can find graphical web browser that displays multimedia content of text, graphics, audio and video, and text web Page 50 http//www. psexam. com Contribution of Suresh Khanal for PS Exam browser that displays only text. Internet Explorer, Netscape, Firefox are graphical web browser and Lynx is a well known text browser. Figure 55 Mozilla Firefox Figure 56 Netscape Navigator http//www. psexam. com Page 51 Contribution of Suresh Khanal for PS Exam Figure 57 Internet Explorer F igure 58 Google Chrome Page 52 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Dialup Connection Dialup connection is a means of connecting user to another computer (ISP) or a network such as the Internet with a modem equipped computer. IP AddressIP Address is an identifier for particular machine on a particular network. It is part of scheme to identify computers on the Internet. IP addresses are a set of numbers separated with periods. Figure 59 IP Address Structure Figure 60 IP Address and Subnet Mask http//www. psexam. com Page 53 Contribution of Suresh Khanal for PS Exam worldly concern Name A domain name is a way to identify and locate computers connected to the Internet. This is a text name of a computer in network or Internet. Domain names are converted to IP Addresses to locate computers and resources. URL URL stands for Uniform Resource locater that identifies a particular Internet resource.URL help the user to locate web page, gopher service, library cata log and image or text file locations. URLs are the standard addressing system of the www. A complete URL provides the web client with all the information it needs to contact a server and make a request for information. URLs are divided into three basic parts Example http//www. psexam. com/download. htm a. Protocol (http//) The information appearing before the colon in any URL indicates the type of information server or protocol. For example http// indicates that the server to be connected is a www server. b. Domain name (www. psexam. com) The second piece of information is the address of the server. In this example psexam. om is the name of the machine at PS Exam in world wide web. c. Resource name (download. htm) The third piece of information is the path to the actual document requested. In this example the URL indicates that the document in the system directory and is named download. htm. Web Browsing or Surfing Browsing or Surfing is the process of visiting different web site s on the Internet hosted by various organizations. Page 54 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Search Engine The search engine is an interactive tool to help people locate information via the www and it is interface between the user and underlying database.The most popular search engines are Alta Vista Exite, Lycos, Yahoo , Google, Ask etc. Figure 61 Yahoo, Ask, MSN, Google Search Engines http//www. psexam. com Page 55 Contribution of Suresh Khanal for PS Exam Figure 62 Alta Vista Search Engine Figure 63 Lycos Page 56 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Meta Search Engine A web meta searcher is a tool that helps users to locate information available via the ball Wide Web. Web meta-serchers provide a single interface that enables users to search many different search engines, listes and databases simultaneously. Some meta search engines are Albany. net, Clnet (search. om), Cyberland, Eureaka , Savvysearch and so on. Figure 6 4 Meta Search Engine Internet Access We can access to the Internet in one of two basic ways, dialing into an Internet Service Providers (ISP) computer or with a direct connection to an ISP. Connecting to ISP by dialing their hunting number (phone number) is called Dial-up connection. We require a username, password and ISPs hunting number to configure Dial up Connection. http//www. psexam. com Page 57 Contribution of Suresh Khanal for PS Exam Extranet An Extranet is a type of Intranet (Internal TCP/IP Network) that has been selectively opened to a firms suppliers, customers. IntranetAn intranet can be defined as a network connecting an affiliated set of clients using standard internet protocols, esp. TCP/IP and HTTP or as an IP-based network of nodes behind a firewall, or behind several firewall connected by secure, possibly virtual, networks. Web Index A web index is designed to assist users in locating information on the World Wide Web. Web indexes are also referred to as catalogs or directories. A web index collects and organizes resources available via the www. Some of the web indexes are Yahoo , Megallan, Apollo etc. Figure 65 Web Index Page 58 http//www. psexam. com Contribution of Suresh Khanal for PS Exam HypertextThe hypertext allows for the integration of text, graphics, audio and video on a web pate. This can make it very easy to browse and very exciting to view. A web page may have colorful graphics integrated with textual information. Links on a web page may take you to other web pages, record sonds, or digital video clips. A single click on any hyperlink allows you to follow the link to the specified resource. Figure 66 Hypertext and Hyper Link Email Electronic Mail (Email) is one of the most popular & powerful communication tools on the Internet. It is an efficient and effective means of network communication. Email allows you to communicate with people across the globe via electronic media (computer). Email addressAn Email Address identifies a person and the computer for the purpose of exchanging electronic mail message. Example emailprotected com http//www. psexam. com Page 59 Contribution of Suresh Khanal for PS Exam The email address contains three parts a. Username The admin in example. b. Domain name of organization The psexam in example c. Top Level Domain The com in example Signature Figure 67 Email Client Interface Inbox It is an element of Email Application which collects all incoming mails. Outbox It is an element of Email Application which collects all outgoing mails, if it is created and sent in offline. Page 60 http//www. psexam. com Contribution of Suresh Khanal for PS Exam TrashThis is an element of Email Application that holds all the deleted emails. Figure 68 New Email Message CC CC stands for courtesy copy or Carbon Copy. It is an element of Email used to watch the additional recipients when the mail sent needs to be acknowledged to them. http//www. psexam. com Page 61 Contribution of Suresh Khanal for PS Exam BCC BCC stands for Blank Carbon Copy. It is similar to CC but the address of other receivers will not be shown to the receiver. Reply A reply is the response of an email you receive. After you read a mail and need to reply it you can use this feature. Forward A mail received can be sent to be other recipients known as forwarding. AttachmentsThe documents created in other applications such as word, excel can be sent along with the email message. These documents that are sent with email is known as attachment. Documents, audio/video files, hie files etc. can be sent as attachment along with email message. Bounced When a mail sent cant reach to destination and returns back, this is known as bounced. This happens often when the recipients address is wrong or the server at the recipients end is down or recipients inbox is full. Netiquette It is essential for all users on the internet to recognize that they are responsible for their own individual actions while using the net. Netiquette is simply the use of common courtesy and polite behavior while using the net. EmoticonsThe convention of expressing feeling or a joke in symbolic form by user in Email or Chatting for example for smiling for winking for frowning etc are emoticons. Page 62 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Figure 69 Emoticons http//www. psexam. com Page 63 Contribution of Suresh Khanal for PS Exam Wish you best of luck Page 64 http//www. psexam. com Contribution of Suresh Khanal for PS Exam Visit New PS Exam Better Interface and greater possibility to share and interact. dont forget to subscribe http//new. psexam. com ICT Trends A Blog about blogging pass the path of Suresh Khanal in blogging, promoting and monetize blogs. http//www. icttrends. com http//www. psexam. com Page 65